1. Field of the Invention
The present invention relates to a mobile positioning apparatus capable of accurately positioning a current position of a mobile body, for example, in a building where a GPS (global positioning system) cannot be used.
2. Description of the Related Art
In a navigation field, where a GPS is mainly used, a technique for covering a positioning error using map matching in a case where the GPS cannot be used has been proposed mainly as an application of a car navigation system.
Most of the map matching techniques use moving path network information which treats a crossing point as a node and a moving path as a straight line, and which is used as map information to perform map matching to cover a positioning error as disclosed in Patent Documents 1 to 4 and Non-Patent Documents 1, 2, 3, and 5 as described later.
Therefore, the conventional map matching techniques work correctly in an orderly environment such as one including straight lines and corners. However, for example, in an indoor environment having a complicated structure, it is difficult and impractical to create map information such as a road network, and thus a map matching techniques cannot be used effectively.
In addition, the movement of a human as a mobile body is smaller than a car, and the moving direction thereof changes finely. Therefore, a map matching technique based on a simple linear matching is not adequate for a human positioning purpose. For example, according to the pedestrian positioning system disclosed in Non-Patent Document 6 described later, a collision determination with respect to the movement vector is performed on a path network with some width, and a handling method of a collision corrects the collision point to an edge of the path network.
When a positioning apparatus for navigating a mobile body is implemented, a dead reckoning device for cumulatively estimating the movement vector of the mobile body has a problem in that errors are cumulatively accumulated with the passage of time.
In view of this, the positioning apparatus based on the dead reckoning device needs to provide correction information about a position to improve the positioning accuracy. As means for providing such correction information, for example, there is provided a method for using position correction means relying on an external artificial environment. An example of this method includes correction means for correcting the position by embedding a radio frequency identification (RFID) tag in the environment and detecting this tag. Such correction means has a problem in that a need for working over the external environment increases a deployment cost for putting the use environment in place.
Patent Document 1: JP-A-2005-226999;
Patent Document 2: JP-A-2007-121139;
Patent Document 3: U.S. Pat. No. 6,856,895;
Patent Document 4: U.S. Pat. No. 6,108,603;
Non-Patent Document 1: Slides No. 19 and No. 20 at http://www.fpoir.org/OPEN/FORUM11_DRkonishi—040820.pdf;
Non-Patent Document 2: “Navigation System” written by Arai and Washino, issued by Sankaido, pp. 60-63;
Non-Patent Document 3: http://www.novatel.com/Documents/Papers/File37.pdf;
Non-Patent Document 4: “Personal positioning based on walking locomotion analysis with self-contained sensors and a wearable camera,” Masakatsu Kourogi, Takeshi Kurata, Proceedings of International Symposium on Mixed and Augmented Reality (ISMAR2003), pp. 103-112, 2003;
Non-Patent Document 5: “Estimation of Ambulatory Activity Utilizing Portable Instruments” The society of Instrument and Control Engineers, Tohoku Chapter, 222nd (Jun. 29, 2005), Document No. 222-10; and
Non-Patent Document 6: “Development of Pedestrian Positioning System by Autonomous Navigation”, Papers and Proceedings of the Geographic Information Systems Associations”, Vol. 10, pp. 389-392, 2001.